The present invention relates to a temperature control device for an internal combustion engine. The temperature control device is applied to a system that includes an internal combustion engine, a cooling circuit, an electric pump, a water temperature sensor, and an ambient temperature sensor. The internal combustion engine has an engine passage, which is a passage for coolant. The cooling circuit is arranged outside the internal combustion engine and is coupled to the engine passage. The electric pump circulates the coolant. The water temperature sensor is arranged in the internal combustion engine. The ambient temperature sensor detects the ambient temperature, which is the temperature of gas surrounding the internal combustion engine.
For example, International Publication No. WO2011/111174 discloses a control device that drives an electric water pump (an electric pump) and detects the presence or absence of water temperature decrease when the difference between the detected values of a water temperature and an intake air temperature (an ambient temperature) is greater than or equal to a predetermined value at the start of the internal combustion engine. The device determines that at least one of the water temperature sensor and the intake air sensor (an ambient temperature sensor) is abnormal when the water temperature does not decrease after the electric water pump is driven.
This device utilizes the behavior that the coolant and the ambient air will reach thermal equilibrium when the internal combustion engine is in the stopped state and determines that a sensor is abnormal on the condition that the difference between the detected value of the water temperature sensor and the detected value of the ambient temperature sensor is large at the start. However, the coolant and the ambient air do not reach thermal equilibrium when heating treatment is performed on the coolant of the internal combustion engine by a heater such as a block heater mounted on the internal combustion engine while fuel supply to the internal combustion engine is stopped. Since the block heater is used to heat the coolant held in the internal combustion engine, the coolant temperature outside the internal combustion engine converges to a near value of the ambient temperature. Thus, the water temperature near the water temperature sensor decreases when the electric pump is driven. For this reason, when the water temperature detected by the water temperature sensor decreases with driving of the electric pump, it is determined that the large difference results from heating treatment by a heater such as the block heater. Thus, false abnormality determination can be avoided.
As described above, the point in time at which the water temperature detected by the water temperature sensor drops due to driving of the electric pump is when the coolant that has received little heat from a heater such as the block heater reaches the water temperature sensor. For this reason, when the electric pump is driven for an extended period of time beyond the time point, the electric pump is driven for a longer time than normal time necessary for abnormality determination. This increases time necessary for warm-up completion of the internal combustion engine. However, International Publication No. WO2011/111174 does not describe stopping of the electric pump after driving of the electric pump.